1. Field of the Invention
The invention relates in general to a hinge mechanism, and more particularly to an auto-lock hinge mechanism.
2. Description of the Related Art
There are various compact electronic devices having flippers, which can be opened to a specific size to make the device easy to operate when it is in use, and can be closed for protection when the device is not in use. For example, the flipper protects the keypad from inadvertent entries and prevents the screen from being damaged or exposed to dust. The cellular flip phone has become in wide demand not only because it has the aforementioned advantages, but also because its flipper is adapted to accommodate a variety of distinguished appearances for aesthetic purposes.
Please refer to FIG. 1A, which shows a flip phone. The flip phone 100 mainly includes a main body 110 and a flipper 120. The flipper 120 is coupled with the main body 110 by the hinge mechanism 130 and can pivotally rotate relative to the main body 110 along the direction of arrow sign in FIG. 1 to be in an opened position or a closed position. Combining a cam with the hinge having a spring is a common design for the hinge mechanism 130, so that the flipper 120 can steadily stay in the opened position or the closed position due to the elasticity of the spring. In practice, the cam can be so easily worn out that the force imposed on the spring for compression is insufficient to produce enough elasticity of the spring. Additionally, the user who is about to open or close the flipper 120 would have to impose a force to turn the flipper 120 to move across the dead point until the flipper 120 is fixedly positioned by means of the elasticity of the spring. Those two conditions of the traditional cam-spring type hinge mechanism might cause great inconvenience for users who want to operate the phone easily with one hand.